The short answer is found in Paul’s first letter to the Corinthians. He wrote in 15:3-5:
“For I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures, that he was buried, that he was raised on the third day in accordance with the Scriptures, and that he appeared to Cephas, then to the twelve.”
Notice: The gospel is “of first importance”, not the Trinity or end times, not church government or ways to do communion, nor anything else. The gospel is the most important element of our faith. He reminded them to keep the main thing the main thing. The same is true for us.
So, if we are to keep the gospel the main thing, then what do we do when my family is falling apart, or I lose my job, or discover someone I love has cancer? Remember the gospel. The gospel is just as important after you trust Christ as before.
Here’s how: When we believe that Jesus is our Lord and Savior, we are united to him and have been adopted by his Father. We are “in him” and we are “sons of God”. Remembering that we are “in him” helps us realize that he is present with us everywhere we go. He is “a very present help in trouble” (Psalm 46:1) Remembering that we have been adopted by him reminds us that the Holy Spirit sealed us into into God’s family and is the guarantee of our inheritance until we acquire possession of it. (Ephesians 1:14) This means he will never abandon nor forsake us because he loves us.
These truths are comforting and assuring. When we ponder them in times of crisis, a peace which surpasses understanding washes over us and enables us to rest easier. It enables us to be joyful in the midst of sorrow and to be hopeful in the face of despair.
This is the reason we remember the gospel! Preach it to yourself daily.